Afghan President Hamid Karzai's half brother – a powerful figure in the country's south – has been assassinated at his home by a trusted bodyguard.

Afghan officials say Ahmad Wali Karzai was shot and killed Tuesday by a senior member of his security detail in Kandahar city. The gunman, who was identified as Sardar Mohammad, was then killed by Wali Karzai's bodyguards.

Officials say Mohammad was a longtime friend of Wali Karzai, and both men were from the same village of Karz. Mohammad was said to be meeting privately with Wali Karzai when he shot the president's brother in the head and chest.

The Taliban claimed responsibility for the assassination. But Afghan officials said it was not clear whether Wali Karzai's killing was related to the insurgency or to an internal feud.

In Kabul, Afghan President Hamid Karzai told reporters the killing of his younger brother represents the suffering of all Afghan people. The Afghan leader traveled to Kandahar later in the day for his brother's burial, set for Wednesday.

The commander of U.S. and NATO forces in Afghanistan, David Petraeus, condemned the murder of Wali Karzai and said NATO forces will support the Afghan government's efforts to bring those responsible to justice.

The Obama administration also condemned Wali Karzai's death “in the strongest possible terms.” White House spokesman Jay Carney said Tuesday the U.S. will work with Afghan authorities as they investigate the killing.

U.S. Secretary of State Hillary Clinton said she called President Karzai to extend her deepest condolences. She said that “for too long, the people of Afghanistan have suffered under the threat of violence, intolerance and extremism.” Clinton added that Washington remains committed to supporting the government and people of Afghanistan in their struggle for peace.

Wali Karzai survived at least two previous attempts on his life in recent years. In May 2009 insurgents attacked his motorcade, killing one of his bodyguards. Wali Karzai also escaped an earlier attack on his provincial council facilities in Kandahar.

The United Nations said in a recent report that more than half of all assassinations across Afghanistan since March were carried out in Kandahar city.

Also Tuesday, Italian defense officials said a roadside bomb killed an Italian soldier in western Farah province. Early Wednesday local time, an International Security Assistance Force member was killed by a roadside bomb in southern Afghanistan. The nationality of that soldier was not immediately released.